IAMGOLD Corporation announced an updated Mineral Resource Estimate (MRE) for the Nelligan Joint Venture Project (Nelligan) (IAMGOLD: 75%, Vanstar Mining Resources Inc. (Vanstar): 25%), located 60 kilometres southwest of Chibougamau, Quebec, Canada. Highlights: Nelligan Joint Venture Project updated MRE comprises (on a 100% basis using a $1,500 per ounce gold price): 72.2 million tonnes of Indicated Mineral Resources averaging 0.85 grams of gold per tonne for 1.97 million ounces of gold. 114.1 million tonnes of Inferred Mineral Resources averaging 0.88 grams of gold per tonne for 3.24 million ounces of gold.

Mineral Resources have increased by 92% in tonnage, with a 15% decline in gold grades, for an overall gain of 63% in metal content ­ relative to the 2019 Mineral Resource estimate. Additional infill drilling completed from 2020 to 2022 and refinement of the deposit and structural models contributed to the conversion of 62% of Inferred Mineral Resources to an Indicated Mineral Resource category relative to the 2019 Mineral Resource estimate. Potential highlighted for further resource expansion.

The current estimated Mineral Resources have increased by 92% in tonnage, with a 15% decline in gold grades due to a reduction in the calculated cut-off grade from 0.50 g/t Au to 0.35 g/t Au, for an overall gain of 63% in contained gold. The updated MRE for the Nelligan Project used all available validated data, and includes results incorporated into the resource model from the 2020 to 2022 drilling programs (53 holes for a total of 22,045 metres drilled), as well as an additional 24 historic drill holes previously located outside mineralized domains, for a total of 84,490 metres in 267 diamond drill holes. Drill holes are variably spaced from 35 to 100 metres apart in the core resource area.

The deposit was modelled using Leapfrog to create domains using lithology, structure and alteration type (or assemblage) and intensity, with gold grade continuity analysis of each domain. The mineralized domain model comprises 5 main gold-bearing domains (Renard Footwall, Renard, Z36, Liam and Dan) cut by a northeast- striking post-mineralization fault which locally cuts and offsets several domains. The estimate was prepared using a block model approach (10.0 x 5.0 x 5.0 metres block dimensions) employing Ordinary Kriging (OK) interpolation constrained by 3D wireframes using hard domain boundaries during estimation.

A Datamine Studio NPVS Scheduler Mine Planning Software was run on the block model to constrain the resource and to support the CIM requirement that Mineral Resources have "reasonable prospects for eventual economic extraction". Pit slopes in rock were assumed at 45° and at 18.4° in overburden and the resource estimate assumes a long-term gold price of US$1,500 per ounce. Gold recoveries are assumed at 83% as indicated by metallurgical test work completed to date.

Only mineralization contained within the optimized pit shell has been included in the resource estimate. The resource estimate was completed by SRK Consulting (Canada) Ltd. ("SRK") with an effective date of December 31, 2022 and is reported at a 0.35 g/t Au cut-off grade. The resource estimation process has identified a number of areas with potential for resource expansion along strike, at depth and in areas where drill hole spacing remains too wide to classify resources at this time.

These areas will be assessed to guide future resource delineation drilling programs. Planning is well advanced for the 2023 exploration program and IAMGOLD will soon initiate its diamond drilling program of approximately 10,000 metres. The objectives of the drilling program include: testing for extensions to expand the known resources in specific areas; infill drilling to continue to convert Inferred Resource to the Indicated category; and evaluation of newly defined exploration targets. Regional exploration activities and future exploration programs continue to be guided by the Nelligan Resource geological model and the incorporation and compilation of exploration data to refine geological, geochemical and structural exploration models to help identify and prioritize additional targets within the large project land package.